diff --git a/IP.java b/IP.java
index d77b909..d0b3a81 100644
--- a/IP.java
+++ b/IP.java
@@ -58,6 +58,20 @@ public static void load(String filename) {
         }
     }
 
+    public static void load(String filename, boolean strict) throws Exception {
+        ipFile = new File(filename);
+        if (strict) {
+            int contentLength = Long.valueOf(ipFile.length()).intValue();
+            if (contentLength < 512 * 1024) {
+                throw new Exception("ip data file error.");
+            }
+        }
+        load();
+        if (enableFileWatch) {
+            watch();
+        }
+    }
+
     public static String[] find(String ip) {
         int ip_prefix_value = new Integer(ip.substring(0, ip.indexOf(".")));
         long ip2long_value  = ip2long(ip);
@@ -85,7 +99,7 @@ public static String[] find(String ip) {
             lock.unlock();
         }
 
-        return new String(areaBytes, Charset.forName("UTF-8")).split("\t");
+        return new String(areaBytes, Charset.forName("UTF-8")).split("\t", -1);
     }
 
     private static void watch() {
@@ -166,4 +180,4 @@ private static long int2long(int i) {
         }
         return l;
     }
-}
\ No newline at end of file
+}
diff --git a/IPExt.java b/IPExt.java
index 3ecdf80..0ffc4ae 100644
--- a/IPExt.java
+++ b/IPExt.java
@@ -35,6 +35,20 @@ public static void load(String filename) {
             watch();
         }
     }
+    
+    public static void load(String filename, boolean strict) throws Exception {
+        ipFile = new File(filename);
+        if (strict) {
+            int contentLength = Long.valueOf(ipFile.length()).intValue();
+            if (contentLength < 512 * 1024) {
+                throw new Exception("ip data file error.");
+            }
+        }
+        load();
+        if (enableFileWatch) {
+            watch();
+        }
+    }
 
     public static String[] find(String ip) {
         String[] ips = ip.split("\\.");
@@ -50,7 +64,7 @@ public static String[] find(String ip) {
             tmpInt = int2long(indexBuffer.getInt(start));
             if (tmpInt >= ip2long_value) {
                 index_offset = bytesToLong(b, indexBuffer.get(start + 6), indexBuffer.get(start + 5), indexBuffer.get(start + 4));
-                index_length = (0xFF & indexBuffer.get(start + 7) << 8) + (0xFF & indexBuffer.get(start + 8));
+                index_length = ((0xFF & indexBuffer.get(start + 7)) << 8) + (0xFF & indexBuffer.get(start + 8));
                 break;
             }
         }
@@ -66,7 +80,7 @@ public static String[] find(String ip) {
             lock.unlock();
         }
 
-        return new String(areaBytes, Charset.forName("UTF-8")).split("\t");
+        return new String(areaBytes, Charset.forName("UTF-8")).split("\t", -1);
     }
 
     private static void watch() {
@@ -154,4 +168,4 @@ private static long int2long(int i) {
         }
         return l;
     }
-}
\ No newline at end of file
+}
diff --git a/README.md b/README.md
index 65a91ed..59e71a0 100644
--- a/README.md
+++ b/README.md
@@ -14,4 +14,11 @@ IP.find("8.8.8.8");//返回字符串数组["GOOGLE","GOOGLE"]
 
 ```
 
-IPExt的用法与IP的用法相同，只是用来解析datx格式文件。
\ No newline at end of file
+IPExt的用法与IP的用法相同，只是用来解析datx格式文件。
+
+##特别说明
+```java
+IP.java 类仅适用于免费版dat与收费版每周每日版本的dat文件；
+IPExt.java 类适用于收费版每日版本的datx文件；
+```
+区县库代码请查看 https://github.com/17mon/quxianku/